What is IPv6?
IPv6 stands for Internet Protocol version 6. Developed by the Internet Engineering Task Force (IETF), IPv6 is used to replace IPv4 because IPv4 restricts Internet development due to address exhaustion. IPv6 not only offers more network address resources but also allows more types of devices to connect to the Internet.
Does Alibaba Cloud Domain Name System (DNS) support IPv6?
Yes, Alibaba Cloud DNS supports IPv6. You can configure AAAA records on the DNS Settings page of the Alibaba Cloud DNS console to allow visitors to access websites by using IPv6 addresses. All DNS servers of Alibaba Cloud DNS also support IPv6.
How does Alibaba Cloud DNS resolve a subdomain if I configure both an IPv6 address and an IPv4 address for the subdomain?
The IPv6 address is returned for a DNS query only if the client of a visitor supports IPv6.
1. Example of DNS record configurations:
Record type | Hostname | DNS request source | Record value |
AAAA | www | Default | ff03:0:0:0:0:0:x:x |
A | www | Default | 1.1.x.x |
DNS resolution results:
If the client of the visitor supports both IPv6 and IPv4, the client sends two DNS queries for an IPv6 address and an IPv4 address to the local DNS server, the local DNS server forwards the two DNS queries to Alibaba Cloud DNS, and then Alibaba Cloud DNS returns the IPv6 and IPv4 addresses to which the domain name is mapped. The client determines which address to return to the visitor. In most cases, the client returns the IPv6 address to the visitor.
If the client of the visitor supports only IPv6, the client sends a DNS query for an IPv6 address to the local DNS server, the local DNS server forwards the DNS query to Alibaba Cloud DNS, and then Alibaba Cloud DNS returns the IPv6 address to which the domain name is mapped. In the end, the client returns the IPv6 address to the visitor.
If the client of the visitor supports only IPv4, the client sends a DNS query for an IPv4 address to the local DNS server, the local DNS server forwards the DNS query to Alibaba Cloud DNS, and then Alibaba Cloud DNS returns the IPv4 address to which the domain name is mapped. In the end, the client returns the IPv4 address to the visitor. The IPv4 address can be in the format of 1.1.x.x.
2. Example of DNS record configurations:
Record type | Hostname | DNS request source | Record value |
AAAA | www | Regions outside the Chinese mainland | ff03:0:0:0:0:0:x:x |
A | www | Default | 1.1.x.x |
If the client of the visitor supports both IPv6 and IPv4 and the client is located in a region outside the Chinese mainland, the client sends two DNS queries for an IPv6 address and an IPv4 address to the local DNS server, the local DNS server forwards the DNS queries to Alibaba Cloud DNS, and then Alibaba Cloud DNS returns both the IPv6 and IPv4 addresses to which the domain name is mapped. The client determines which address to return to the visitor. In most cases, the client returns the IPv6 address.
If the client of the visitor supports only IPv4 and the client is located in a region outside the Chinese mainland, the client sends a DNS query for an IPv4 address to the local DNS server, and the local DNS server forwards the DNS query to Alibaba Cloud DNS. However, Alibaba Cloud DNS cannot respond to the DNS query because no IPv4 address is configured for the resolution lines of Alibaba Cloud DNS outside the Chinese mainland.
If the client of the visitor supports only IPv4 and the client is located in the Chinese mainland, the client sends a DNS query for an IPv4 address to the local DNS server, the local DNS server forwards the DNS query to Alibaba Cloud DNS, and then Alibaba Cloud DNS returns the IPv4 address to which the domain name is mapped. In the end, the client returns the IPv4 address to the visitor. The IPv4 address can be in the format of 1.1.x.x.
If the client of the visitor supports both IPv6 and IPv4 and the client is located in the Chinese mainland, the client sends two DNS queries for an IPv6 address and an IPv4 address to the local DNS server, and the local DNS server forwards the DNS queries to Alibaba Cloud DNS. However, Alibaba Cloud DNS returns only the IPv4 address to the local DNS server because only IPv4 addresses are configured for the default resolution lines of Alibaba Cloud DNS. In the end, the client returns the IPv4 address to the visitor. The IPv4 address can be in the format of 1.1.x.x.